Sosa-Gmez DR, Moscardi F
Embrapa-National Soybean Research Center, Londrina, PR, 86001-970, Brazil.
J Invertebr Pathol. 1998 Mar;71(2):115-20. doi: 10.1006/jipa.1997.4716.
Isolates of Metarhizium anisopliae (CNPSo-Ma12) and Beauveria bassiana (CNPSo-Bb56) were tested under field conditions as biological control agents of soybean stink bugs (Nezara viridula, Piezodorus guildinii, and Euschistus heros). Kaolin-based powder formulations of M. anisopliae or B. bassiana were applied to soybean plots at a rate of 1.5 x 10(13) conidia per ha. After treatment, field cages (0.25 m2) were placed in plots and stink bug adults were introduced into the cages. Mycosis for both P. guildinii and N. viridula was initially observed 7 days postapplication in the 1991 season and at 15 days postapplication in the 1992 season. For E. heros, mortality was detected on day 8 and on day 20 in 1991 and 1992, respectively. In 1991, infection levels of 48 and 41% were achieved at day 30 for P. guildinii and N. viridula, respectively, whereas the infection level in E. heros reached only 33%. In 1992, mortality caused by M. anisopliae on the three stink bug species was lower than that observed in 1991, with cumulative mycosis at day 30 being 15, 17, and 20% for P. guildinii, N. viridula, and E. heros, respectively. The 1991 season was humid and warm, whereas in the 1992 season there was an 8-day drought spell (<75% relative humidity (RH)) after application, suggesting that %RH was responsible for an earlier occurrence and a higher prevalence of both fungi on stink bug species in the 1991 trial. Despite the higher deposition of B. bassiana on the plants (17 colony forming units [CFU] per mm2 of leaflet) 1 day after application compared to M. anisopliae (5.1 CFU per mm2 of leaflet), B. bassiana was less efficient against stink bugs than M. anisopliae. Field results were confirmed through laboratory bioassays, in controlled conditions (T = 26 +/- 1.5 degreesC, 90% RH, and 8D:16L light regimen). The mean time to mortality by M. anisopliae was 4.3 +/- 0.2 days for P. guildinii, 4. 6 +/- 0.2 days for N. viridula, and 7.4 +/- 0.5 days for E. heros. E. heros was less susceptible and P. guildinii was the most susceptible species to M. anisopliae. Since these species usually occur as a complex in soybean in Brazil, these results represent important information toward the development of entomopathogenic fungi as microbial insecticides of these pests. Copyright 1998 Academic Press.
在田间条件下，对绿僵菌（CNPSo-Ma12）和球孢白僵菌（CNPSo-Bb56）的分离菌株作为大豆蝽象（稻绿蝽、豆荚草盲蝽和英雄蝽）的生物防治剂进行了测试。将基于高岭土的绿僵菌或球孢白僵菌粉剂制剂以每公顷1.5×10¹³个分生孢子的速率施用于大豆田块。处理后，在田块中放置田间网笼（0.25平方米），并将蝽象成虫引入网笼。在1991年季节施药后7天以及1992年季节施药后15天首次观察到豆荚草盲蝽和稻绿蝽感染真菌病。对于英雄蝽，在1991年和1992年分别于第8天和第20天检测到死亡。1991年，在第30天，豆荚草盲蝽和稻绿蝽的感染率分别达到48%和41%，而英雄蝽的感染率仅达到33%。1992年，绿僵菌对三种蝽象的致死率低于1991年，在第30天，豆荚草盲蝽、稻绿蝽和英雄蝽的累积真菌病感染率分别为15%、17%和20%。1991年季节湿润温暖，而在1992年季节，施药后出现了8天的干旱期（相对湿度<75%），这表明相对湿度是1991年试验中两种真菌在蝽象物种上更早出现和更高流行率的原因。尽管施药1天后球孢白僵菌在植物上的沉积量（每平方毫米小叶17个菌落形成单位[CFU]）高于绿僵菌（每平方毫米小叶5.1个CFU），但球孢白僵菌对蝽象的防治效果不如绿僵菌。通过在受控条件（温度T = 26±1.5℃、相对湿度90%、光照周期8小时光照:16小时黑暗）下的实验室生物测定证实了田间试验结果。绿僵菌导致豆荚草盲蝽死亡的平均时间为4.3±0.2天，导致稻绿蝽死亡的平均时间为4.6±0.2天，导致英雄蝽死亡的平均时间为7.4±0.5天。英雄蝽对绿僵菌的敏感性较低，而豆荚草盲蝽是对绿僵菌最敏感的物种。由于这些物种在巴西大豆田中通常混合发生，这些结果为将昆虫病原真菌开发为这些害虫的微生物杀虫剂提供了重要信息。版权所有1998年学术出版社。
